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rcu: Check for idle-loop entry while in RCU read-side critical section 

The inner idle loop is an extended quiescent state for all flavors
of RCU, but there have been recent bug involving use of RCU read-side
primitives from within the idle loop.  Therefore, this commit enlists
lockdep-RCU to detect attempts to enter the inner idle loop while in
an RCU read-side critical section, emitting a lockdep-RCU splat if so.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2012-01-12 13:08:18 -08:00 committed by Paul E. McKenney
parent 30fbcc90b0
commit c44e2cddac
1 changed files with 11 additions and 0 deletions
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11
kernel/rcutree.c
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@ -366,6 +366,17 @@ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval)
atomic_inc(&rdtp->dynticks); atomic_inc(&rdtp->dynticks);
smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */
WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
/*
* The idle task is not permitted to enter the idle loop while
* in an RCU read-side critical section.
*/
rcu_lockdep_assert(!lock_is_held(&rcu_lock_map),
"Illegal idle entry in RCU read-side critical section.");
rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map),
"Illegal idle entry in RCU-bh read-side critical section.");
rcu_lockdep_assert(!lock_is_held(&rcu_sched_lock_map),
"Illegal idle entry in RCU-sched read-side critical section.");
} }
/** /**